


Salty but Sweet

by sparkandwolf (thatnerdemryn)



Category: Teen Wolf (TV)
Genre: Alternate Universe - Merpeople, Big Brother Derek Hale, First Meetings, Flirting, Fluff, Love at First Sight, M/M, Mermaid Stiles Stilinski
Language: English
Status: Completed
Published: 2020-06-04
Updated: 2020-06-04
Packaged: 2021-03-04 01:07:56
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,006
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24545131
Author URL: https://archiveofourown.org/users/thatnerdemryn/pseuds/sparkandwolf
Summary: “Honey, I know you want to believe mermaids are real, but you can’t just--” There was another splash behind him and Derek was going to ignore it, but Cora’s face lit up in a giant grin.“I wouldn’t have let her drown, pops,” a voice said as he turned. He pushed Cora behind him and she tried to surge forward and the - the mermaid? - scoffed in his direction. “In what fairy tale are mermaids kidnappers?”
Relationships: Derek Hale/Stiles Stilinski
Comments: 24
Kudos: 407





	Salty but Sweet

**Author's Note:**

> Prompt: Merpeople and tooth rotting fluff if you can! Thank you!

Derek watched as Cora ran along the beach, her tiny feet kicking up sand and splashing at the waves rolling to the shore. He loved bringing Cora out to play, to soak in the rays and cool down in the ocean current. It wasn’t often that they could spend time together with Derek constantly on the go, so spending time with his little sister was always special. His summers off seemed to be the only thing that kept him sane. 

“Der!” Her bright voice chimed through the sea breeze. Derek rested the book on the rocks beside him and put all of his attention toward her. “There’s mermaid’s in the ocean!” She said, pointing out toward the wide expanse of the ocean. Derek nodded, wishing he had the imagination of a child again, and walked toward her. 

“Of course there are,” he agreed, picking her up and holding her on his hip. 

“I saw one. His name is Stiles. He’s bathing on the rocks because mermaids need the sun just as much as humans do.” Derek couldn’t help but chuckle as she said the words so matter-of-factly.

“What color is Stiles’ tail?” Derek asked, placing her back on her feet. She squatted down and drew a figure into the sand, accentuating the long tail with tiny scales. She peered back up at Derek, her face contorted in concentration, and Derek’s heart burst from how adorable she was. 

“A lot of colors. This part here,” she pointed to the very bottom of the tail, “is a really dark red. And then it gets lighter and lighter until here.” She pointed at his waist just before a wave washed up and erased her picture. She pouted and took off running toward the end of the beach before climbing up at a few dangerous looking rocks. Derek sprinted after her, calling her name with every step. She disappeared over the rocks and Derek’s stomach dropped when he heard a loud splash. 

“Cora!” He screamed as he sprinted and launched himself up on the rocks. He looked down in the water, unable to find her bright pink bathing suit, his panic growing with every second. 

“Derek, you scared him,” Cora pouted, crossing her arms in front of her chest. He pulled her into his arms and held onto her tightly as she squirmed. “You scared my mermaid away!” She yelled as Derek finally released her. 

“You can’t run away like that, Cor! There was no one over here to stop you from falling into the ocean. You could’ve been hurt!” Cora rolled her eyes and Derek was annoyed at how much it looked like him. 

“Stiles is an adult and could’ve saved me if I fell. But I didn’t fall! I just wanted to see his tail again!” Derek huffed and crossed his own arms over his chest, mimicking her position. 

“Honey, I know you want to believe mermaids are real, but you can’t just--” There was another splash behind him and Derek was going to ignore it, but Cora’s face lit up in a giant grin.

“I wouldn’t have let her drown, pops,” a voice said as he turned. He pushed Cora behind him and she tried to surge forward and the - the mermaid? - scoffed in his direction. “In what fairy tale are mermaids kidnappers?” Derek tilted his head and furrowed his brow because what else was he supposed to do. There was a man, a beautiful man, a freckled chest glistening with ocean water, and a… tail. A tail, red gradient just as Cora had described, that was splashing in and out of the water slowly. Derek was mesmerized immediately. 

“Do most people have a normal reaction when they see you for the first time?” Derek retorted. The mermaid gaped, kicking up his fin to toss water directly into the center of Derek’s chest. He sputtered and swiped his hand over his chest, Cora giggling brightly behind him. She snuck around Derek and before he could stop her, she slipped on one of the rocks jutting from the sand. The mermaid caught her before she fell and tugged her to his side, Cora nestling in snugly. 

“Careful, little one,” he murmured, swiping a hand over her hair. “There’s only so much this mermaid can save you from.” Cora beamed up at him and Derek wasn’t sure he had ever seen her so happy. 

“How can I get a tail like you, Stiles?” She asked, her eyes turned pleading. Derek watched the two of them, trying to remember when he fell and slammed his head on the rocks because all of it was obviously a dream. 

Stiles’ bubbling laughter tossed him out of his thoughts and Derek thought it was one of those most beautiful things he had ever heard. “I’ll tell you when you’re older, lovebug,” he said softly, glancing up at Derek. “I bet your dad here wouldn’t quite like me influencing your mind that way.” He glanced up at Derek with a wink that had Derek’s face reddening. 

“Ew!” Cora exclaimed, a look of disgust contorting across her small face. “Derek is my  _ brother _ , Stiles. Not my dad!” Derek couldn’t help but chuckle as she stuck her tongue out and shook her head viciously. Stiles’ laughter chimed again and Derek was snapped back into reality, if that was what he could call it. 

“Mermaid,” Derek started, only to be cut off by a sharp glare from his sister. 

“His name is Stiles, Der!” She retorted, crossing her arms over her chest. 

“Yeah, Der, my name is Stiles. And I am a mermaid, yes.” Derek wanted to smack the smirk off of Stiles’ face almost as much as he wanted to kiss him. Stiles seemed to notice his internal struggle and tilted his head in amusement. Derek realized Stiles was waiting for him to finish his earlier sentence and blushed darker. 

“Stiles,” he said a lot softer than he intended, “you’re telling me that mermaids are real?” Stiles nodded, pulled Cora closer into his side as she swiped a hand down his tail that seemed to shimmer in the sunlight. “And that all this time, they have been swimming along the beach I go to five times a week?” Stiles blushed at that and Derek raised an eyebrow. “You know I come here,” Derek said. It should’ve been a question, but the look on Stiles’ face said everything he needed to know. “Have you seen me before?” He pried. A surge of pride washed through him when Stiles ducked his head and rolled his eyes. 

“He knew exactly who you were! It’s why he let me play with him and was so nice!” Stiles glared at Cora before splashing her with his tail, looking away as if his fin had a mind of its own. Cora squealed in delight, reaching down toward the water to splash him back. She started tumbling forward but that time Derek didn’t panic because he knew Stiles would catch her. The immediate trust should have scared him more than it did. He slid his tail underneath her knees and kicked her back up to sitting, rolling his eyes that were filled with fondness. 

“So, Stiles, how often do you come around here?” Derek said as he leaned back against the rock, overlapping his legs as he stared down at the two of them. He realized the insanity of everything that was happening and decided to embrace it for what it was, his eyes boring into Stiles’ that seemed to glisten like the sea. 

Stiles rolled his eyes and turned his face out to the ocean, but Derek still saw his blush. “My pod lives about a mile from here and this is the nearest beach with rocks that we can sun on and it has the added perk of being far away from the major road and--” Derek cut him off with a look that had Stiles rolling his eyes again. Cora’s laughter filled the air as she reached into a small pool of water. 

“You talk a lot for a mermaid, Stiles,” she commented, staring intently down at the shells she held delicately in her hand. Stiles gaped at her before looking back at Derek who was barely containing his laughter. 

“You’ve talked to a lot of mermaids then?” Stiles teased, his fin dipping into the water before dumping a small amount of the liquid on her head. Derek couldn’t stop his thoughts from trailing to whatever else Stiles could do with his tail. He blushed at the thought and looked out over the sea as the sun started setting. He didn’t realize it had gotten so late and was surprised by how much he didn’t want to leave. 

“Cor, we have to get you back,” he said regretfully, rubbing the back of his neck when Cora’s lower lip started trembling. He chanced a glance at Stiles and saw a bit of sadness in his eyes and he could feel his resolve slipping the longer their eyes stayed connected. 

“But Derek!” She said with a stomp, crossing her arms over her chest to accentuate the pout on her lips. Stiles pressed his lips together to stop himself from laughing and Derek knew that feeling all too well. Cora was a spitfire but she was adorable when she was angry. 

“We can come back. In a few days when I have you next, maybe we can meet Stiles right here,” Derek offered, a shyness in his tone as his eyes flashed to Stiles again. The overwhelming fear of rejection was quickly obliterated by the bright smile that crossed Stiles’ face. 

“I’m here every day, little one. And even if I wasn’t, I’d come back for you.” Derek knew he was talking to Cora, but Stiles’ eyes never left his. Heat surged through Derek, his heart clenching in his chest and his stomach flipping in ways he didn’t think possible. 

“Every day?” Cora asked, her face softening as she sniffled. Derek saw the hope in her eyes and thought his own held the same. Stiles nodded and held his arms out to her as she jumped forward into them. He squeezed her tight, with his entire body, and Derek didn’t think he could possibly warm more. 

“Let me tell you a secret,” Stiles started. He glanced at Derek with a smirk before cupping Cora’s ear in his hands so Derek couldn’t hear the words. Derek rolled his eyes but leaned against the rock behind him to give them the semblance of privacy. When Stiles pulled away, Cora nodded eagerly and pressed a wet kiss to his cheek. Stiles beamed at her and pushed her windswept hair back before placing a soft kiss on her forehead. 

“I’ll see you soon, Stiles!” Cora waved happily, making her way over the rocks and leaving Derek gaping behind her. 

“What did you say to her?” Derek asked, a hesitant excuse not to leave. Stiles smiled up at him and Derek reveled in the brightness and joy behind it. 

“That’s between me and the little one, Derek,” Stiles said softly. Derek nodded and with one last smile, turned to leave. Before he made it to the edge of the rocks, Stiles called after him. “Come back tomorrow,” Stiles said. It was a question that he knew Derek couldn’t say no to. He nodded and gasped as Stiles pushed off the rock and dove into the water. It was the most graceful movement Derek had ever seen and for the first time in a long while, he was speechless. 

“You coming, Derek?” Cora asked, running back over to where he stood, mouth fallen open. Derek nodded and continued his trek, taking Cora’s hand in his as they made their way to the other side of the beach. 

“So, what do you think of Stiles?” Derek asked playfully as he strapped her into her car seat. Cora giggled before looking up at Derek with wide, optimistic eyes. 

“Can we keep him?” Cora asked. 

And who was Derek to say no?

**Author's Note:**

> I have never written mermaid fluff before so I hope you enjoyed these two instantly enamored beings <3
> 
> I have a [Tumblr](https://sparkandwolf.tumblr.com) specifically for my Sterek obsession so feel free to follow it for updates and snippets and other Sterek content and use my ask to send me prompts, coda ideas, or just scream with me about Sterek. 
> 
> Also, feel free to follow my [Twitter](https://twitter.com/thatnerdemilyj) and let me know what you think. 
> 
> Please, please, please let me know your thought in the comments and leave kudos if you enjoyed it!


End file.
